There has been proposed a refrigeration cycle system for air-conditioning apparatuses, which is provided with a differential pressure-type throttle device instead of a capillary tube serving as the throttle device. The differential pressure-type throttle device is configured to optimally control a pressure of a refrigerant between an outlet of a condenser and an inlet of an evaporator in order to efficiently operate a compressor in accordance with an outside air temperature. Moreover, in a refrigeration cycle system that is capable of changing the number of revolutions of the compressor, the differential pressure-type throttle device is also configured to optimally control the pressure of the refrigerant in accordance with the number of revolutions of the compressor from the viewpoint of power saving. For example, one end of the throttle device through which the refrigerant is injected is joined to a primary duct connected to the condenser, and another end thereof from which the refrigerant is discharged is joined to a secondary duct connected to the evaporator.
As shown in PATENT DOCUMENT 1, for example, such a differential pressure-type throttle device includes: a valve body which adjusts an opening degree of a valve port of a housing; a guide skirt which has a plurality of holes and guides a movement of the valve body; and a coil spring which biases the valve body toward a space at an inlet port of the housing. In the above-described differential pressure-type throttle device, so-called hunting may occur which is a phenomenon where the valve body repeats a series of actions of instantaneously moving in a closing direction due to a reduction in a pressure on the primary duct side inside the housing, upon moving in a direction to increase the opening degree of the valve port of the housing.
In order to prevent the hunting, as shown in PATENT DOCUMENT 2, for example, there has been proposed a differential pressure-type throttle device having awing (which is called an anti-vibration spring (see FIG. 4 and FIG. 5) in PATENT DOCUMENT 2) provided with a plurality of elastic sliding contact pieces. The wing made of a metal is provided in a spring chamber in a state of being pressed by use of a spring against a spring receiving portion of the valve body provided at the inlet port of a main body. Thus, when the valve body is moved, the a plurality of elastic sliding contact pieces of the wing move in sliding contact with an inner wall surface of the spring chamber, thereby suppressing an abrupt movement of the valve body. Therefore, the hunting is prevented.